Removal Efficiency Of Manganese Research Articles

Preparation and Characterization of Sodium Alginate Based Composite Beads for Manganese Removal

The main objective of this study was to characterize and investigate the performance of sodium alginate (SA)-based composite beads as adsorbents for manganese removal from the aqueous solution. In this study, 2% (w/v) of sodium alginate solution was prepared. The SA beads, SA-PCC (SA-P) beads, SA-BMnO (SA-B) beads, and SA-PCC-BMnO (SA-PB) beads were formed by mixing with ionic gelation in a crosslink solution of calcium chloride (CaCl2). The composite beads were characterized using FESEM and thermogravitmetry analysis (TGA). According to FESEM micrographs, all the adsorbents were spherical in shape, with an average diameter of 1.40 mm to 1.50 mm. The results of TGA demonstrated that SA-PB beads had improved thermal stability and exhibited the highest manganese removal efficiency, with a percentage of removal of 96.14%.

Manganese Detection and Removal from Surface Water: A case study from Mengkubau Water Treatment Plant

The study of water contamination, especially in developing countries, has become more crucial in recent years as the demand for clean, drinkable water has increased. Brunei Darussalam’s primary water supply comes from surface waters, and each year, BND $ 9 to 10 million is spent on chemicals for water treatment. Recently, the Mengkubau dam, which supplies water to the Brunei Muara District, has been upgraded in terms of its height to meet the increased demand. Because of this, the amount of manganese in raw water went up, especially during the rainy season. This caused problems for the Mengkubau Water Treatment Plant (MWTP). So, a study was done to find out where the extra manganese was coming from and how it could be stopped to help solve the problems in a more cost-effective and long-term way. Rock samples from the dam and rainfall data, as well as the data for manganese concentration in the raw water, were collected to understand the source of manganese. The results showed that the rocks contributed to the manganese concentration in the raw water, which increased by almost nine folds. Furthermore, rainfall influences manganese concentration because concentration is higher in the rainy season compared to the dry season. Also, an experiment was done to see if water lettuce, or Pistia stratiotes, could be used as a sustainable and cost-effective treatment. The efficiency of manganese removal through water lettuce varies depending on the exposed weather condition. The highest removal efficiency of 97% was achieved when the water lettuce was placed in the shade.

Induced crystallization for the simultaneous removal of hardness-iron–manganese in groundwater: An experimental study

Hardness, iron, and manganese are common groundwater pollutants, that frequently surpass the established discharge standard concentrations. They can be effectively removed, however, through induced crystallization. This study has investigated the effectiveness of the simultaneous removal of hardness-iron-manganese and the crystallization kinetics of calcium carbonate during co-crystallization using an automatic potentiometric titrator. The impacts pH, dissolved oxygen (DO), and ion concentration on the removal efficiency of iron and manganese and their influence on calcium carbonate induced crystallization were assessed. The results suggest that pH exerts the most significant influence during the removal of hardness, iron, and manganese, followed by DO, and then the concentration of iron and manganese ions. The rate of calcium carbonate crystallization increased with pH, stabilizing at a maximum of 10−10 m/s. Iron and manganese can be reduced from an initial level of 4 mg/L to <0.3 mg/L and 0.1 mg/L, respectively. The removal rate of iron, however, was notably higher than that of manganese. The DO concentration correlates positively with the removal of iron and manganese but has minimal impact on the calcium carbonate crystallization process. During the removal of iron and manganese, competitive interactions occur with the substrate, as increases in the concentration of one ion will inhibit the removal rate of the other. Characterization of post-reaction particles and mechanistic analysis reveals that calcium is removed through the crystallization of CaCO3, while most iron is removed through precipitation as Fe2O3 and FeOOH. Manganese is removed via two mechanisms, crystallization of manganese oxide (MnO2/Mn2O3) and precipitation. Overall, this research studies the removal efficiency of coexisting ions, the crystallization rate of calcium carbonate, and the mechanism of simultaneous removal, and provides valuable data to aid in the development of new removal techniques for coexisting ions.

Effect of pH by Manganese Salts and Natural Organic Matter on Nanofiltration Membrane Fouling

This research aimed to determine the removal performance of manganese affected from solution pH of combined manganese salts with natural organic matter (NOM) using commercial nanofiltration (NF) membrane. The filtration experiments were tested under a dead-end filtration test cell. Variational factors used in this study were the types of manganese salts (i.e. manganese chloride (MnCl2), manganese sulfate (MnSO4), and manganese nitrate (Mn(NO3)2)) with the solution pH of 3, 5, and 7, and ionic strength of 0.01 mol/L. Water samples were prepared with NOM concentration of 10 mg/L, while the operating pressure was operated constant at 60 psig. Experimental results found that the MnSO4 salt provided the highest manganese removal efficiency of 95%, while the removal efficiencies of MnCl2 and Mn(NO3)2 were about 84.86% and 70.7%, respectively. Solution fluxes were not significantly different. In the presence of NOM concentration of 10 mg/L, solution pH of 3–7, it was found that low solution pHs for all conditions provided the highest manganese removal. The removals of NOM were relatively high more than 97%. The mathematical fouling model was done with cake filtration model (CFM) due to NOM accumulation on NF membrane surface.

A Study on Evaluation of Manganese Removal Efficiency by Oxidant types Based on Experimental Data

Objectives : The purpose of this study was to investigate the treatment efficiency according to the oxidant types for dissolved manganese in the inflow of raw water into the water treatment plant in Korea.Methods : Three types of oxidant were selected: chlorine, ozone, and potassium permanganate. Experimental factors influencing manganese removal efficiency were determined as dissolved manganese concentration in raw water, dose, water temperature, pH, and contact time. In addition, total experimental schemes were designed according to the design of experiments method. According to the designed analysis method, the mentioned factors were used as multi variables on which evaluate the manganese removal efficiency.Results and Discussion : When using chlorine, the effect of pH was the greatest, followed by dose, water temperature, and contact time in order to have a significant effect on removal efficiency. In the case of using ozone, the pH effect was relatively large at low concentration of dissolved manganese, and the dose effect was found to be greater as the concentration was increased. Also, when potassium permanganate was used, the effect of pH, contact time and temperature was insignificant, while the effect of dose was the greatest for manganese removal.Conclusion : The optimum dose of chlorine is about three times to secure a removal rate of about 40 to 80%. The optimum dose of ozone was 1.0 to 1.6 mg/L, and it was found that a removal rate of at least 40% or more could be secured. Also, the optimum dose of potassium permanganate is 1.7 to 2.5 times of the dissolved manganese concentration, and it is possible to secure a removal rate of at least 60%.

Process optimization of rice straw-derived activated biochar and biosorption of heavy metals from drinking water in rural areas

The Indo-Gangetic plain of northern India is known for prevalent rice farming. Due to the lack of a rice straw waste management system, a large volume of rice straw is burned in the field. Therefore, we add value to rice straw by converting it into activated biochar and utilizing it to remove toxic metals from natural water. In this work, single-step physical activation (CO2 and H2O) of rice straw was planned and optimized the activation process parameters to get better biochar yield and surface area. The biochar activation parameters were optimized using the central composite design method. The CO2 activated biochar has an optimum surface area and product yield of 399.99 m2/g and 26.79 %, whereas H2O activated biochar has an optimum product yield and surface area of 31.53 % and 300 m2/g. The SEM analysis shows that CO2 activated biochar has a more uniform porous structure than H2O activated biochar. Cost analysis revealed that CO2 and H2O activated biochar had a lower manufacturing cost of 1.287 and 1.672 U.S. $/kg, respectively compared to other adsorbents. Arsenic and manganese removal efficiency in natural water was found to be greater than 95 % for both activated biochar.

Halloysite Nanotube-Enhanced Polyacrylonitrile Ultrafiltration Membranes: Fabrication, Characterization, and Performance Evaluation.

This research focuses on the production and characterization of pristine polyacrylonitrile (PAN) as well as halloysite nanotube (HNT)-doped PAN ultrafiltration (UF) membranes via the phase inversion technique. Membranes containing 0.1, 0.5, and 1% wt HNT in 16% wt PAN are fabricated, and their chemical compositions are examined using Fourier transform infrared (FTIR) spectroscopy. Scanning electron microscopy (SEM) is utilized to characterize the membranes' surface and cross-sectional morphologies. Atomic force microscopy (AFM) is employed to assess the roughness of the PAN/HNT membrane. Thermal characterization is conducted using thermal gravimetric analysis (TGA) and differential thermal analysis (DTA), while contact angle and water content measurements reveal the hydrophilic/hydrophobic properties. The pure water flux (PWF) performance of the porous UF water filtration membranes is evaluated at 3 bar, with porosity and mean pore size calculations. The iron (Fe), manganese (Mn), and total organic carbon (TOC) removal efficiencies of PAN/HNT membranes from dam water are examined, and the surfaces of fouled membranes are investigated by using SEM post-treatment. Mechanical characterization encompasses tensile testing, the Mori-Tanaka homogenization approach, and finite element analysis. The findings offer valuable insights into the impact of HNT doping on PAN membrane characteristics and performance, which will inform future membrane development initiatives.

Bioremediation of iron and manganese heavy metal polluted soil by mixed culture of Acetobacter tropicalis and Lactobacillus fermentum

The research aim was to determine the growth response of mixed cultures of Acetobacter tropicalis and Lactobacillus fermentum in Stone Mineral Salt solutions (SMSs) and soil containing Acid Mine Drainage (AMD) in controlled batches. The first stage was the cultivation in SMSs followed by preparation of the pollutant source and sensitivity test. The second phase was the removal of heavy metals from iron and manganese in AMD by mixed bacterial cultures in SMSs with the contact time for 48, 96, 144, 192 hours, and pH 2, 3, 5, 7. The third stage was the removal on soil media with the same contact time. Research result showed that the sensitivity test of bacterium was resistant to heavy metals iron and manganese. The highest removal efficiency of iron and manganese was 94.89% at a contact time of 96 hours, while the highest removal efficiency at pH 7 was 93.79%. The removal of iron and manganese heavy metals on soil had a removal efficiency of 69.91% at a contact time of 144 hours. This study showed that a mixed culture of Acetobacter tropicalis and Lactobacillus fermentum could be an effective bacterium in removing heavy metals from iron and manganese in AMD-contaminated soil.

EVALUATION OF THE EFFICIENCY OF SORBENTS-CATALYSTS FOR THE PURIFICATION OF WATER FROM MANGANESE COMPOUNDS

The condition of sources and central water supply systems does not guarantee the required quality of drinking water. A large part of the population of Ukraine uses drinking water that does not meet hygienic requirements according to various indicators. Manganese compounds are quite often present in natural waters. Their quantitative content can vary in a wide range, depending on the region, it can be 5-6 mg/dm3. Manganese in underground waters is presented as ion Mn2+, salts of which are soluble. To remove manganese from water one should transfer it to insoluble state by oxidation. Today, there are a number of typical technologies of demagnetization of water. Many works have also been published which describe the purification of water from manganese ion. It is worth noting that with a high content of manganese compounds in water, their removal is a rather difficult task. Removal of manganese compounds from water can be implemented using the ion exchange method, which consists of filtering water through loading in salt or acidic form. At the same time, softening and desalination of water can occur simultaneously. Therefore, the ion exchange method should be used for comprehensive water purification, softening, and removal of manganese compounds. In order to study the oxidizing capacity of catalytic loading with respect to manganese compounds in water were used as a catalytic load KU-2-8 cationite modified with magnetite and manganese oxide in H+, Na+, and Ca2+ forms. To modify cationite with magnetite under static conditions, it was treated with a solution containing a mixture of Fe2+ and Fe3+ ions in a ratio of 1:2. The research was also carried out on the preparation of catalysts based on cationites by modifying them with manganese compounds. The purpose of this article is to evaluate the efficiency of manganese removal from water when using a catalyst sorbent. The article presents the results of research on water purification from manganese compounds using sorbents-catalysts modified with iron and manganese compounds. It was established that in static and dynamic conditions, complete extraction of manganese ions can be achieved using sorbents based on polymer resin and magnetite. When using cation exchange resin modified with magnetite, the removal of Mn2+ ions from aqueous solutions occurs both due to ion exchange, regardless of the form of the ion exchanger, and due to oxidation on the catalyst (magnetite) in the presence of dissolved oxygen. Modified cation exchange resin in Na+ form leads to the extraction of manganese due to sorption and oxidation of Mn2+. In this case, sorption of calcium and magnesium ions, which is known to be accompanied by an increase in pH. The pH of the medium increased, which increased the efficiency of oxidation of manganese ions on magnetite. Under these conditions, the sorbent catalyst provides complete removal of manganese ions due to catalytic oxidation and sorption of manganese ions on magnetite.

Effects of organic substrates on sulfate-reducing microcosms treating acid mine drainage: Performance dynamics and microbial community comparison

Bioremediation techniques utilizing sulfate-reducing bacteria (SRB) for acid mine drainage (AMD) treatment have attracted growing attention in recent years, yet substrate bioavailability for SRB is a key factor influencing treatment effectiveness and long-term stability. This study investigated the effects of external organic substrates, including four complex organic wastes (i.e., sugarcane bagasse, straw compost, shrimp shell (SS), and crab shell (CS)) and a small-molecule organic acid (i.e., propionate), on AMD removal performance and associated microbial communities during the 30-day operation of sulfate-reducing microcosms. The results showed that the pH values increased in all five microcosms, while CS exhibited the highest neutralization ability and a maximum alkalinity generation of 1507 mg/L (as CaCO3). Sulfate reduction was more effective in SS and CS microcosms, with sulfate removal efficiencies of 95.6% and 86.0%, respectively. All sulfate-reducing microcosms could remove heavy metals to different degrees, with the highest removal rate of >99.0% observed for aluminum. The removal efficiency of manganese, the most recalcitrant metal, was the highest (96%) in the CS microcosm. Correspondingly, SRB was more abundant in the CS and SS microcosms as revealed by sequencing analysis, while Desulfotomaculum was the dominant SRB in the CS microcosm, accounting for 10.8% of total effective bacterial sequences. Higher abundances of functional genes involved in fermentation and sulfur cycle were identified in CS and SS microcosms. This study suggests that complex organic wastes such as CS and SS could create and maintain preferable micro-environments for active growth and metabolism of functional microorganisms, thus offering a cost-efficient, stable, and environmental-friendly solution for AMD treatment and management.

NaClO-based rapid sand filter in treating manganese-containing surface water: Fast ripening and mechanism

Recently, seasonal manganese contamination in the surface water is capturing ever-increasing attention and has posed significant challenges to the safety of water supply in the conventional drinking water treatment plants. This study aimed to develop new strategies to enhance the manganese removal by the sand filter. The synergistic effects of filter material type, filter layer thickness, filtration rate, and NaClO addition on the manganese removal performance, were systematically investigated. The results indicated that modified zeolite exerted the highest adsorption capacity (5.200 mg/g) for manganese. Introducing the NaClO oxidation would effectively improve the manganese removal efficiency (from 32 % to 97 %) by the modified zeolite filter compared to the control system at the filtration rate of 8 m/h, owing to the fast formation of catalytic oxidation capability. Accordingly, the effective layer thickness of modified zeolite can be shortened from 100 cm to 10–20 cm to engineer a double-layer filter consisting of both a thin modified zeolite layer and a thick natural quartz sand layer. Besides, NaClO involvement would neutralize the adverse effects of manganese removal caused by the filtration rate increase, and facilitate the formation of auto-catalytic manganese oxides (MnOx) with rough, heterogeneous, and porous surface morphology, as well as numerous tremella-like and sponge-type structures, which was related to the fast removal of manganese. These findings are full of significance in developing simple, practical, and cost-effective strategies for seasonal manganese contamination.

Effect of salt solution treatment on impurity removal: A case study on phosphogypsum

AbstractThis study gives a brief demonstration of impurity removal efficiency upon salt solution treatment of phosphogypsum (PG). The experimental set up has been designed according to a multi‐variable Box–Behnken Design (BBD) with stirring time, solid: liquid (PG:salt solution) ratio and temperature as the conducted in various salt solutions. PG sample has been treated with sea water, 5% NaCl and 10% NaCl solutions according to the BBD matrix. Fluoride (F), copper (Cu), manganese (Mn), and nickel (Ni) amounts in the PG sample have been measured upon pre‐ and post‐treatment with salt solutions. Among other operating conditions, temperature has been the dominant factor on fluoride removal efficiency, and responses for the factors determined in the experiment runs indicated that a significant correlation could be established between temperature and fluoride removal, sea water being the most efficient salt solution. Higher copper, manganese, and nickel removal efficiencies have been observed in single salt NaCl solution systems however no significant correlation could be established between factors. Results indicate that pre‐treatment of PG located near coastal regions with sea water can be a cost‐effective approach and applicable on industrial scale when fluoride removal is of importance.

Effects of organics concentration on the gravity-driven membrane (GDM) filtration in treating iron- and manganese-containing surface water

Iron and manganese contamination in the surface water is posing great challenges to the drinking water treatment supply, especially in the complex cases of organics involvement. Gravity-driven membrane (GDM) filtration equipped with the dual functions of ultrafiltration and biocake layer, conferred promising potentials in the removals of iron and manganese. This study evaluated the effects of organics concentrations on the removal performance of iron and manganese, as well as on the flux stabilization during GDM long-term filtration. The results indicated that stable flux level and the removal efficiency of manganese initially increased with the increase of organics concentration in the feed water, and then decreased. The moderate concentration of organic compounds in the feed water would positively facilitate the microbial activities and benefit to engineering a heterogeneous and porous biocake layer on the membrane surface, contributing to the highest improvements of stable flux (6.3 L m−2 h−1), while high concentration of organic compounds in the feed water would result in the increase in the thickness and EPS concentration of the biocake layer, leading to a flux reduction. Furthermore, the moderate concentration of organic compounds in the feed water was also beneficial to the manganese removal (> 94.6%) due to the more accumulation of auto-catalytic oxidation manganese oxides (MnOx) within the biocake layer and the improved biological degradation, however, further increase of organics concentration would deliver a negative impact on the manganese removal owing to the wrapping of MnOx by the organic substances. Overall, these findings provide practical and acceptable strategies to the selections of pre-treatments prior to GDM and promote its extensive application in treating the iron- and manganese-containing surface water.

Study on the preparation of manganese oxide filter media for catalytic oxidation removal of ammonium and manganese in high alkalinity groundwater: The effect of copper and cobalt doping

Owing to the low efficiency of catalytic oxidation of ammonium and manganese in high alkalinity groundwater by manganese oxide filter column, the effect of doping copper (Cu) and cobalt (Co) on catalytic activity was investigated. A pilot-scale filter column system was used in this experiment. The catalytic oxidation activities of manganese oxide filter media prepared at different Cu and Co concentrations (0, 0.1, 1.0 mg/L) in raw water were compared. The results showed that the removal efficiency of ammonium by the filter column increased from 65% to 100% due to low Cu doping, while the removal efficiency of manganese decreased from 95% to 60% due to high Cu doping. Low Co doping was beneficial to the start-up period of the filter column and the effluent ammonium concentration reached the standard on the 8th day. In addition, X-ray diffraction (XRD) and Scanning electron microscopy coupled energy dispersive spectroscopy (SEM-EDS) results showed that the high alkalinity of water led to the formation of a large amount of calcium carbonate on the surface of the filter media. Combined with X-ray photoelectron spectroscopy (XPS) analysis, it was found that the conversion of different valence manganese species caused by Cu and Co doping and the Cu and Co elements with different valence were the key factors determining the catalytic activity of manganese oxide filter media. Cu2+/Cu+ and Co3+/Co2+ electron cycles also participated in the electron transfer process of catalytic reaction. This study provides a research idea for solving the pollution problem of ammonium and manganese in high alkalinity water.

Bioinspired modeling and biogeography-based optimization of electrocoagulation parameters for enhanced heavy metal removal

Electrocoagulation is an effective wastewater treatment process for the removal of heavy metals. This study focuses on deriving optimal conditions for removing heavy metals, viz. Lead (Pb), Cobalt (Co), and Manganese (Mn) from simulated wastewater by investigating removal efficiency and energy consumption of electrocoagulation process. Five operational parameters namely pH (2–10), current density (0.076–0.189 A/cm2), inter-electrode distance (3–7 cm), solution temperature (30–70 °C) and charging time (5–25 cm) have been analyzed. To improve the treatment of heavy metals, a novel coupled approach, namely Artificial neural network - non-dominated sorting Biogeography based optimization (ANN-NSBBO), has been proposed. Using the experimental data, a feed-forward backpropagation ANN model is used with removal efficiency and energy consumption as the outputs. Optimal values of operational parameters for maximum removal efficiency and minimum energy consumption were obtained using multi-objective NSBBO over the trained ANN model. True pareto fronts for Cobalt, Lead and Manganese were obtained after 100 iterations of the optimization algorithm. The maximum removal efficiency of 98.66% was obtained for Cobalt at the electrical energy consumption of 0.204 kWh. Minimum energy consumption for electrocoagulation of Lead (5.34 x 10−6 kWh) gave 82.48% removal efficiency. The maximum removal efficiency of Manganese (101.238%) was achieved at 7.64 pH, 0.084 A/cm2 current density, 3.188 cm inter-electrode distance, 47.49 °C solution temperature, 19.758 min charging time, and 0.145 kWh energy consumption. The non-dominated optimum tradeoff between removal efficiency and energy consumption provides clarity on operating conditions for the electrocoagulation process. The proposed approach of enhancing heavy metal treatment could assist municipalities, industries, and the scientific communities in achieving the United Nation's sustainable development goal of heavy metal remediation.

Manganese Stress Adaptation Mechanisms of Bacillus safensis Strain ST7 From Mine Soil.

The mechanism of bacterial adaption to manganese-polluted environments was explored using 50 manganese-tolerant strains of bacteria isolated from soil of the largest manganese mine in China. Efficiency of manganese removal by the isolated strains was investigated using atomic absorption spectrophotometry. Bacillus safensis strain ST7 was the most effective manganese-oxidizing bacteria among the tested isolates, achieving up to 82% removal at a Mn(II) concentration of 2,200 mg/L. Bacteria-mediated manganese oxide precipitates and high motility were observed, and the growth of strain ST7 was inhibited while its biofilm formation was promoted by the presence of Mn(II). In addition, strain ST7 could grow in the presence of high concentrations of Al(III), Cr(VI), and Fe(III). Genome-wide analysis of the gene expression profile of strain ST7 using the RNA-seq method revealed that 2,580 genes were differently expressed under Mn(II) exposure, and there were more downregulated genes (n = 2,021) than upregulated genes (n = 559) induced by Mn stress. KAAS analysis indicated that these differently expressed genes were mainly enriched in material metabolisms, cellular processes, organism systems, and genetic and environmental information processing pathways. A total of twenty-six genes from the transcriptome of strain ST7 were involved in lignocellulosic degradation. Furthermore, after 15 genes were knocked out by homologous recombination technology, it was observed that the transporters, multicopper oxidase, and proteins involved in sporulation and flagellogenesis contributed to the removal of Mn(II) in strain ST7. In summary, B. safensis ST7 adapted to Mn exposure by changing its metabolism, upregulating cation transporters, inhibiting sporulation and flagellogenesis, and activating an alternative stress-related sigB pathway. This bacterial strain could potentially be used to restore soil polluted by multiple heavy metals and is a candidate to support the consolidated bioprocessing community.

Manganese removal from zinc sulfate electrolyte by electro-oxidation using Pb-Ag anode

ABSTRACT The optimum conditions for manganese dioxide (MnO2) removal were investigated in two simulated conditions, purification and electrowinning, using a Pb-0.7 wt.% Ag electrode. Linear sweep voltammetry and Cyclic voltammetry tests were conducted to study the effect of temperature and concentrations. SEM-EDS and XRD were employed to study the surface characterisations and chemical compositions. The results revealed that the electrowinning operating conditions are more appropriate than the purification conditions for MnO2 removal. The highest current efficiency of manganese removal was 21% which was obtained in the EW electrolyte at 125 A m−2 at 40°C after 2 h of electrolysis. The Current Efficiency was increased significantly at lower Mn ion concentrations (0.1–1.0 g L−1) while it stayed constant beyond the concentration of 1.0 g L−1. The results showed that an increase in temperature depolarised the oxygen evolution reaction and the addition of Mn2+ suppressed formation of PbO2 on anode surface.

Simultaneous removal of fluoride, manganese and iron by manganese oxide supported activated alumina: characterization and optimization via response surface methodology.

Fluoride, iron and manganese simultaneous exceedance of standard can be observed in groundwater in northeastern China. This work aims to apply a highly efficient method combining adsorption and oxidation for the synchronous removal of the inorganic ions. An innovative adsorbent (manganese-supported activated alumina) was synthesized by the impregnation method and showed a significant adsorption capacity better than that of fresh activated alumina. The characterization (scanning electron microscope; Brunauer, Emmett and Teller; X-ray diffraction and Fourier transform infrared spectroscopy) results verified the successful introduction of MnOOH and MnO2, and the improvement of surface microstructure enhanced the removal ability. The effect of single factors, such as pH value, reaction time or dosage on the removal performance has been verified. The maximum removal efficiencies of fluoride, iron and manganese were optimized via Response surface methodology considering the independent factors in the range of MO@AA dosage (5-9 g/L), pH (4-6) and contact time (4-12 h). Noted that compared with control, MO@AA exhibited 59.4% of improved fluoride performance. At pH of 5.79, contacting time of 12 h and 8.21 g/L of MO@AA, fluoride, iron and manganese removal were found to be 91, 100 and 23%, respectively. Herein, MO@AA was distinguished as good applicability for the treatment of fluoride-, iron- and manganese-containing groundwater.

Efficient Removal of Aqueous Manganese (II) Cations by Activated Opuntia Ficus Indica Powder: Adsorption Performance and Mechanism

The adsorption of manganese ions from aqueous solutions by pure and acid-treated Opuntia ficus indica as natural low-cost and eco-friendly adsorbents was investigated. The adsorbents' structures were characterized by powder X-ray diffraction and infrared spectroscopy. Specific surface areas were determined using the Brunauer-Emmett-Tell equation. The study was carried out under various parameters influencing the manganese removal efficiency such as pH, temperature, contact time, adsorbent dose and initial concentration of manganese ion. The maximum adsorption capacity reached 42.02 mg/g for acid-treated Opuntia ficus indica, and only 20.8 mg /g for pure Opuntia ficus indica. The Langmuir, Freundlich and Temkin isotherms equations were tested, and the best fit was obtained by the Langmuir model for both adsorbents. The thermodynamic study shows that chemisorption is the main adsorption mechanism for the activated adsorbent while physisorption is the main adsorption mechanism for the pure adsorbent. The kinetics of the adsorption have been studied using four kinetics models of pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion. Structural analyses indicate the appearance of MnOx oxides on the cellulose fibers. The adsorption mechanisms consist of an electrostatic interaction followed by oxidation of the Mn (II) to higher degrees, then probably by binding to the surface of the adsorbent by different C-O-MnOx bonds.

Insight into synergies between Acinetobacter sp. AL-6 and pomelo peel biochar in a hybrid process for highly efficient manganese removal

The manganese contamination of groundwater is a global issue that needs to be solved urgently. In this study, a hybrid process between pomelo peel biochar(BC) and Acinetobacter sp. AL-6 (strain AL-6) was established to remove manganese from water. The results showed that microbe-biochar composite had removed 98.19% of manganese (800 mg L−1) within 48 h. Compared with two separate systems (biochar, strain AL-6), the co-system (strain AL-6 and BC composite) had an excellent synergy effect on manganese removal. The average removal rate of manganese in the synergistic system was 14.08 mg L−1 h−1, which was 6.41 times higher than strain AL-6, 3.45 times higher than biochar, and even at 2.24 times their sum. In addition, the scanning electron microscope (SEM) and the bioassay indicated that many strains were attached to biochar and had vigorous biological activity. The FTIR results showed that the functional groups of OH, CO, CO, CH2, and CH played a vital role in removing manganese. And the correlation analysis shows that biochar with strains AL-6 has a highly synergistic effect on manganese removal. Meanwhile, the composite material can maintain excellent manganese removal efficiency under different pH conditions. Besides, in the sequence batch reactor (SBR) inoculating with the microbe-biochar composite, more than 96% of manganese was removed, which far exceeded the treatment efficiency of free bacteria in the SBR. Hence, biochar-immobilized AL-6 has great potential and can be applied to degrade manganese polluted wastewater.